morison



(ModeL) v 3 Sheets-Sheefl. D. B. MORISON.

STEAM BOILER FLUE AND FIRE BOX.

No. 477,770. Patented June 28, 1892..

(Model) 3 Sheets-Sheet 2.

' B. MORISON. STEAM BOILER FLUB'AND'PIRB BOX.

N0. 477,770. Patnted June 28-, 1892.

' (ModeL) 3 Sheets-Sheet 3. I D. B. MORISON. -S TBAM BOILER FLUE AND FIRE BOX. 4 No. 477,770.

Patented June 28, 1892,

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UniTEn STATES PATENT Osmon DONALD BARNS MORISON, or HARTLE'POOL, ENGLAND.

STEAM-BOILER 'FLUE AND FIR E-BOX.

SPECIFICATION forming part of LettersPatent No. 477,779, dated June 28, 1892. Application filed September 10, 1se0. ;.senn No. 364,572. (Modeh) Patented in England March 27. 1890, no. 4,806.

To all whom it may concern? Be it known that I, DONALD BARNS MomsON, a subject of the Queen of Great Britain and Ireland, residing at Hartlepool, in the county of Durham, Kingdom of Great Britain and Ireland, have invented Improvements in Steam-Boiler Flues and Fire-Boxes, (which invention has been patented to me in Great Britain, No. 4,806, dated March 27, 1890,) of which the following is a specification.

In the accompanying drawings, Figure 1 is a longitudinal section of one common form of corrugations. Fig. 2 is a similar view of another old form; Figs. 3, 4, and 5 are similar views showing my improvement. Figs. 6 and 7 are longitudinal and transverse sections of a boiler or similar device embodying my improvement.

Boiler flues or fire-boxes of circular crossseetion have been proposed to be made of various forms of longitudinal section, two forms of the corrugated type being usually adopted in practice-win, that in which the corrugations are of uniform kind-for example, as represented in Fig. 1 of the annexed drawings, in which the external corrugations a and the internal corrugations b have practically the same depth, width, and curvature-and that represented by way of example in Fig. 2, in which the corrugations or ridges a project outward and the intervening portion 19 of the flue is cylindrical or, as seen in longitudinal section, straight. In practice I have found both these forms of furnace open to objection. In the form first mentioned, Figxl, the channels 0 between the outwardly-projecting corrugations a, being comparatively narrow, have the eifect of causing concentration of deposit on the water side of the corrugations b, and as these corrugations b are then subjected to greater intensity of temperature on the reverse side1. 6., that against which the fire aetsthan at any other parts of the furnace the material is so distressed that small cracks often develop. The secondly-mentioned form of corrugated flue or fire-box, Fig-.2, is objectionable because, as I have found, the strength given by the outwardly-projecting corrugations a is not uniformly distributed throughout the material between the corrugations, and when solid matter accumulates upon the flue the cylindrical portions 1) between the aforesaid corrugations a are found, practically, to have a tendency to sag or form indentations or pockets.

Now the object of my invention is to obviate the foregoing objections, to which end I construct a flue or fire-box as shown in Fig. 3, which is a longitudinal vertical section of part of a flue or fire-box. In cross-section the flue or fire-box is circular. In longitudinal section the inwardly-projecting corrugations B have much less curvature than the outwardly-projecting ridges or corrugations A. These outwardly-projecting ridges or corrugations A thus form the supporting ridges or corrugations from which the inwardly-projeeting corrugations 13 receive additional strength to resist collapse. The curved form of the inwardly-projecting corrugations asv sists in distributing this additional strength in a uniform manner. The inwardly-projecting corrugations B in a flue or fire-box constructed in accordance with this invention are much less angular than those of the firstnamed form, Fig. 1, and are therefore less liable to the objections enumerated with regard to that form. At the same time the furnace can be more easily scaled and when necessary repaired. As compared with the second'form 8c of flue or fire-box mentioned, Fig. 2, there is in mine no flat part between the ridges or corrugations A A and the strength of the flue or fire-box is more uniformly distributed.

The thickness of the material of which the flue or fire-box is made may be uniform'or it may vary. In Fig. 3 thematerial is shown as of uniform thickness. Figatshows avariable section in which the material is thicker at and on each side of the outwardly-projecto ing ridges A. In Fig. 5 the thickness is greatest at the crown of the outwardly-projecting and supporting ridges A and least at the central portions of the inwardly-projecting parts B, the variation in thickness being symmetri- 5 cal on each side of I each corrugation; The corrugations can be formed in any suitable manner-as, for example, by rolling, as well understood.

, Fig. 6 shows in longitudinal section, to a roo No. 304,973 to Strong and No. 372,487 to Purves, and they illustrate, substantially, the I forms of corrugations first referred to in the above specification, the patent to Strong showing the corrugations made of reverse compass curves, while the patent to Purves shows the projecting parts thickened and curved on 7 their under sides, while the projections are connected by substantially straight in-terve-ning portions, as illustrated in Fig. 2 of the drawings accompanying this specification. It will be seen that my invention differs from these in that the portions A, forming projecting and supporting ridges, are of a curvature much greater than the intermediate projecting corrugations B. The first projections A are substantially compass curves; but the intermediate corrugations B are substantially in the form of a catenary curve. It has been found that these curves present the greatest resistance against collapse of the boiler from pressure, and it is further found that the Ma 1 bility of scale accumulating in this curve is less than in the ordinary compass curves, and

if itvdoes accumulate it can be more readily cleaned or removed from the suspension or catenary curved portion than from the compass-drawn curves. I make no claim to either structure shown in the patents referred to nor to anything shown and described in British Patent No. 4,834, of 1886, but I What I do claim is- 1. A corrugated steam-boiler flue or fire box in which the material between the supporting curved ridges is disposed in the form of corrugations of much less curvature than the supporting-ridges and following, substantially, the line of a catenary curve between the ridges, substantially as described.

2. A corrugated steam-boiler flue or fireboxin which the material between the curved supporting-ridges is disposed in the form of corrugations of much less curvature than said ridges and following, substantially, the line of a catenary curve, the supporting-ridges being of greater thickness on their crowns than the intervening parts, substantially as described.

In testimony whereof I have signed my name to this specification in the presence of two subscribing witnesses.

DONALD BARNS M'ORIS'ON. 

